Michelle Williams lost control on her journey through 'Oz'

Michelle Williams comes from the world of low-budget independent film, so, she said, it took her a while to get her sea legs on the $200-million-plus production of "Oz: The Great and Powerful."

"That was a really hard transition for me to make," the thrice Oscar-nominated actress said at the film's premiere in Hollywood on Wednesday evening. Talking about the film's grandiose sets -- which included seven soundstages -- Williams said she felt anxious about how many people were observing her act.

"I'm conscious of people watching me perform, and I walked onto the set and there must have been 20 different monitors set up," she said. "I realized I wasn't going to be able to control things like I like to."

The film, a prequel to L. Frank Baum's classic "The Wizard Of Oz," explores the back story of the Wizard character. Played by James Franco, the Wizard is a con man more interested in stealing the Emerald City's treasure than helping save the people of Oz from evil. But when he encounters three witches -- played by Williams, Mila Kunis and Rachel Weisz -- he begins to wonder if perhaps his motives have been misplaced.

Franco arrived to the yellow-brick-road-themed carpet via hot-air balloon, which hovered in the air for about 30 minutes, filming a bit for "Jimmy Kimmel Live!" As the actor waited for the late-night talk-show spot to begin, he appeared uncomfortable in the balloon, texting on his phone and taking pictures of fans who had gathered on Hollywood Boulevard.

On set, Franco spent a lot of time observing as well, according to costar Zach Braff. Braff, who plays the monkey that serves as the Wizard's assistant, said both actors-turned-filmmakers spent a lot of time watching director Sam Raimi.

"Both James and I are filmmakers ourselves, and Sam was like the best mentor in the world, teaching us how a movie of this scale is made," Braff said. "In my new film that I'm directing, I have some much smaller-scale little effects people, but I wouldn't have put those in if I hadn't had six months of grad school with Sam Raimi."

At the after-party, Braff was flanked by his statuesque supermodel girlfriend Taylor Bagley, while Kunis holed up with her beau, Ashton Kutcher. Weisz -- who was not with her husband Daniel Craig -- spent time mingling with partygoers, while Williams -- sans boyfriend Jason Segel -- sipped champagne with best friend Busy Phillips in a corner booth.

None of the leading ladies were spotted taking advantage of the free O.P.I. manicure station, where a handful of young women waited in line to have their nails painted with glittery polish inspired by the film.